The invention relates to a yarn cleaner for cleaning out defects from a yarn and, more particularly, to a yarn cleaner having a measuring head for measuring at least one yarn parameter and wherein, wherein cleaning limits are determined for the yarn parameter for indicating the presence of a defect in the yarn so that intolerable defects may be cut out from the yarn.
In the production of yarn, as high a uniformity as possible of the yarn is generally aimed for within narrow tolerances as well as a yarn without visible defects, such as intolerable thick or thin locations in the yarn. In order to achieve this, so-called yarn cleaners are used, which, for example, monitor the diameter of the yarn continuously with a measuring head which operates contactlessly. If, owing to the exceeding of limit values called cleaning limits, an intolerable defect is detected, the defect is cut out of the yarn, the yarn ends are connected again and the production process is continued, as known, for example from German Patent Publication DE 10062479 A1.
In conventional yarn monitoring, a single reference diameter is determined and cleaning limits selected for this. For example it is known from the literature reference “Elektronisches Garnüberwachungssystem Corolab fur Rotor-Spinnspulautomaten Autocoro”, Chemiefasern/Textilindustrie, 40th/92nd Volume, April 1990, in order to determine a reference diameter, to determine an average diameter value of the yarn at the beginning of the measurement at a spinning station over the first yarn meters. This so-called reference diameter is the reference diameter for all further evaluations. Measured actual diameters of the yarn are generally given as a percentage based on the reference diameter.